The synthesis, characteristic ratio C-infinity and glass transition temperature (T-g) of poly(tetrahydrofurfuryl acrylate) (PTHFA) and of poly(2-ethylbutyl acrylate) (P2EBA) are reported. P2EBA has slightly lower flexibility (C-infinity = 9.2) than PTHFA (C-infinity = 8.6), mainly because of the higher bulkiness of its side group and the closer proximity to the main chain. The C-infinity results compared with the corresponding polymethacrylates show an increase in flexibility due to the absence of the a-methyl group. Comparison with poly(methyl acrylate) clearly shows the influence of the bulkiness of the side group on the chain flexibility. The lower T-g of P2EBA than that of PTHFA may be explained by the higher flexibility of the 2-ethylbutyl side group.